Cast iron deterioration with time in various aqueous salt solutions

摘要

The changes with time in the corrosion rate and corrosion current density on a cast iron electrode in various aqueous salt solutions have been carried out using total immersion test and potentiostatic polarization curves. The concentration of salts taken is expected to be present in potable water. The relative behaviour of these salts towards corrosion has also been studied, which is found to be different from previous studies. The total immersion test parameters viz. weight loss, corrosion rate as well as potentiostatic parameters, open circuit potential, I_(corer), Tafel slopes, corrosion rate, have been calculated by standard methods. Besides these the relative increase in corrosion rate with time as well as the percentage to which corrosion rate should be decreased so as to provide protection towards corrosion have also been calculated. It was found that KCl and NaCl are major contributors than MnSO_4, Pb(NO_3)_2, KI and KBr. The relative increase in corrosion is high in KBr, KI, NaNO_3, CaCl_2, and less in Pb(NO_3)_2, NaHCO_3 and CaCO_3 test solutions. For the reliability of results the data has been statistically analysed.